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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 | /* * Copyright 2013, Michael Ellerman, IBM Corp. * Licensed under GPLv2. */ #define _GNU_SOURCE #include <stdio.h> #include <stdbool.h> #include <string.h> #include <sys/prctl.h> #include "event.h" #include "utils.h" #include "lib.h" extern void thirty_two_instruction_loop_with_ll_sc(u64 loops, u64 *ll_sc_target); static void setup_event(struct event *e, u64 config, int type, char *name) { event_init_opts(e, config, type, name); e->attr.disabled = 1; e->attr.exclude_kernel = 1; e->attr.exclude_hv = 1; e->attr.exclude_idle = 1; } static int do_count_loop(struct event *events, u64 instructions, u64 overhead, bool report) { s64 difference, expected; double percentage; u64 dummy; prctl(PR_TASK_PERF_EVENTS_ENABLE); /* Run for 1M instructions */ thirty_two_instruction_loop_with_ll_sc(instructions >> 5, &dummy); prctl(PR_TASK_PERF_EVENTS_DISABLE); event_read(&events[0]); event_read(&events[1]); event_read(&events[2]); expected = instructions + overhead + (events[2].result.value * 10); difference = events[0].result.value - expected; percentage = (double)difference / events[0].result.value * 100; if (report) { printf("-----\n"); event_report(&events[0]); event_report(&events[1]); event_report(&events[2]); printf("Looped for %llu instructions, overhead %llu\n", instructions, overhead); printf("Expected %llu\n", expected); printf("Actual %llu\n", events[0].result.value); printf("Delta %lld, %f%%\n", difference, percentage); } event_reset(&events[0]); event_reset(&events[1]); event_reset(&events[2]); if (difference < 0) difference = -difference; /* Tolerate a difference below 0.0001 % */ difference *= 10000 * 100; if (difference / events[0].result.value) return -1; return 0; } /* Count how many instructions it takes to do a null loop */ static u64 determine_overhead(struct event *events) { u64 current, overhead; int i; do_count_loop(events, 0, 0, false); overhead = events[0].result.value; for (i = 0; i < 100; i++) { do_count_loop(events, 0, 0, false); current = events[0].result.value; if (current < overhead) { printf("Replacing overhead %llu with %llu\n", overhead, current); overhead = current; } } return overhead; } #define PM_MRK_STCX_FAIL 0x03e158 #define PM_STCX_FAIL 0x01e058 static int test_body(void) { struct event events[3]; u64 overhead; // The STCX_FAIL event we use works on Power8 or later SKIP_IF(!have_hwcap2(PPC_FEATURE2_ARCH_2_07)); setup_event(&events[0], PERF_COUNT_HW_INSTRUCTIONS, PERF_TYPE_HARDWARE, "instructions"); setup_event(&events[1], PERF_COUNT_HW_CPU_CYCLES, PERF_TYPE_HARDWARE, "cycles"); setup_event(&events[2], PM_STCX_FAIL, PERF_TYPE_RAW, "stcx_fail"); if (event_open(&events[0])) { perror("perf_event_open"); return -1; } if (event_open_with_group(&events[1], events[0].fd)) { perror("perf_event_open"); return -1; } if (event_open_with_group(&events[2], events[0].fd)) { perror("perf_event_open"); return -1; } overhead = determine_overhead(events); printf("Overhead of null loop: %llu instructions\n", overhead); /* Run for 1Mi instructions */ FAIL_IF(do_count_loop(events, 1000000, overhead, true)); /* Run for 10Mi instructions */ FAIL_IF(do_count_loop(events, 10000000, overhead, true)); /* Run for 100Mi instructions */ FAIL_IF(do_count_loop(events, 100000000, overhead, true)); /* Run for 1Bi instructions */ FAIL_IF(do_count_loop(events, 1000000000, overhead, true)); /* Run for 16Bi instructions */ FAIL_IF(do_count_loop(events, 16000000000, overhead, true)); /* Run for 64Bi instructions */ FAIL_IF(do_count_loop(events, 64000000000, overhead, true)); event_close(&events[0]); event_close(&events[1]); return 0; } static int count_ll_sc(void) { return eat_cpu(test_body); } int main(void) { return test_harness(count_ll_sc, "count_ll_sc"); } |